Designing a Broadband Pump for High-Quality Micro-Lasers via Modified Net Radiation Method

Area of Science:

• Optics and Photonics
• Materials Science
• Energy Science

Background:

• High-quality micro-lasers are crucial for various applications but suffer from poor broadband pump light absorption.
• Cascade energy transfer has recently enabled non-resonant pumping, improving micro-laser and solar-pumped laser performance.

Purpose of the Study:

• To develop a generic theoretical framework for modeling energy transfer in cascade sensitizer-laser gain systems.
• To optimize parameters for low-threshold solar-pumped lasers using this new model.

Main Methods:

• Developed a theoretical model based on linear equations of the modified net radiation method.
• Applied the formalism to compute optimal parameters for low-threshold solar-pumped lasers.
• Validated the model by comparing numerical results with experimental data from a sensitized Nd³⁺:YAG cavity.

Main Results:

• The model accurately describes absorption, emission, and energy transfer in cascade systems.
• Optimal pump absorption for these lasers is below maximal absorption due to interplay between absorption and self-absorption.
• Quantitative agreement was found between theoretical predictions and experimental data.

Conclusions:

• The developed theoretical framework is robust, fast, and of low complexity.
• This work facilitates the optimal design of broadband-pumped high-quality micro-lasers.
• Paves the way for more efficient solar-pumped lasers through modular design of gain and sensitizing components.